Hi all.
Just a few things I do know about that ALL MUCK AND MAGIC Vintage artisan Brit colour case hardening treatment.
The range of colours can in part be changed a small amount by adding other items to the Charcoal /Bone mix such as charred leather, Ivory scrap, ground up animal teeth
By adding varying amounts of Salt Peter (Potassium Nitrate) to the quenching water.
Also how much Air disturbance you introduce in to the quenching water.
Making a Chill, an older term for a piece of metal added to another piece of metal to affect its rate of cooling in a semi controlled way. Just to deviate from the gun subject a little the positioning in the foundry of bearing mould chills was a closely guarded secret in times past especially when it came to casting and supplying the Bronze Mill Stand Brasses for rolling mills. By not getting the chills correct the life of a heavy Mill stand bearing could be drastically reduced. This secrecy also stopped other bearing manufacturers from trying to poach your customer.
To stop colour changing ringing by holes the fitting of a clay plug or a pin to stop the water from entering this then prevents a different rate of temperature change by the hole.
I do bereave that colour case hardening is an art form and not just an industrial process by virtue of the number of times a man does it and the ways he experiments to get a finish particular to him.
